Update TileCache format determination to support TileCache's weird jpg->jpeg

translation correctly. Also, update example to show usage, and tests to test
jpeg instead of testing png incorrectly.


git-svn-id: http://svn.openlayers.org/trunk/openlayers@5100 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/TileCache.js

@@ -52,7 +52,7 @@ OpenLayers.Layer.TileCache = OpenLayers.Class(OpenLayers.Layer.Grid, {
         OpenLayers.Layer.Grid.prototype.initialize.apply(this,
                                                          [name, url, {}, options]);
         this.extension = this.format.split('/')[1].toLowerCase();
-        this.extension = (this.extension == 'jpeg') ? 'jpg' : this.extension;
+        this.extension = (this.extension == 'jpg') ? 'jpeg' : this.extension;
     },    
 
     /**